AP Computer Science The 1996 Reading Process “how the papers were marked” by Dave Slemon,

Clemson University South Carolina, June 1996 All of the 1996 computer papers were marked at Clemson.

11,000 Computer papers were read by 85 readers. l 6200 A - exams l 4800 AB - exams l The reading team consists of: – 1 Chief Reader – 2 Exam Leaders – 12 Question Leaders – 70 Readers

Address from the Chief Reader l the Chief Reader co-ordinates question leaders, and they – create and test all of the rubrics for each question – discuss each question with all 85 readers – the creation of training packs designed to help teach readers to mark consistently. l the Chief Reader alone – oversees all aspects of the reading – decides who gets 5’s, 4’s, 3’s, etc.. one week later in Princeton.

1 question is read per room l Each room is responsible for marking one entire question, (eg., all 6000 of the number 3’s on the A exam). l The ladies in the hall shuttle the papers from room to room. l Black bandages cover previous scores given by other readers on other questions.

The rubric & scoring sheet The rubric is the marking scheme. The readers never put any marks into the student’s booklet; they use their own scoring sheet.

The Question Leaders l One is a college professor and the other is a high school teacher. l They teach the 12 other readers how to grade using the carefully prepared rubric. l Each reader trains on 250 papers before marking one single real paper. Each question has 2 Question Leaders who sit at the front of the room.

Readers l Each reader has one partner. l 25 papers make up 1 pack. l Each paper is read separately by each partner. l Each Reader scores the paper on their persona- lized scoring sheet. l Charts on the wall serve as reminders. The 12 readers in this room are marking the 1995 sequence question.

Reading the same question l Question 4 of the 1995 A paper is being marked in this room. l Documentation is not marked. l Compiler-catching errors are not penalized. l Obobs (off by one bug) lose marks.

Back reading Back reading is usually done by the Question Leaders. The Leaders look for discrepencies between the two scoring sheets. They resolve all discrepencies by conferring with the two Readers who disagreed.

Things that really matter l getting the idea point. l accurate loop counting. l testing all of your cases. l check boundary conditions carefully. l setting the function value correctly.

Things that don’t matter l semicolons l documentation l choice of variable names l indenting l = instead of := l compiler catching syntax errors

Marking the AP Computer Exams at Clemson Univ. in South Carolina the 10 people in this room were responsible for marking on 1994 A paper, Question #3

Common errors l Improper addressing struct CARD { int partNum; apstring description; int quantity; double price; }; CARD index; cin >> partNum; should be: cin >> index.partNum;

Some patterns over the years l Computer Science AB Exam – My students rarely finish the 40 multiple choice questions; finishing the ones you do correctly is more important! – Usually there are 4 long answer questions, with some of the questions having parts (a) - (d). 1. A case study question, e.g. BigInt 2. A string or a 2-D Array or a File. 3. A linked list question. 4. A tree question.

Interesting Observations ‘...but no guarantees’ l Computer Science A Exam – My students rarely finish the 40 multiple choice – There are usually 4 long answer questions. 1. A 2-D array, with nested-looping. 2. A string or file question. 3. A case study question e.g. BigInt 4. A record-based question using struct.

The Scoring Sheet

+1 idea +1 init +1 accumulation +1 correct 4/4

+1 idea +1 init +0 accumulation (function name used as local variable) +1 correct -0.5 usage (i/o) 3/4

+1 idea +1 init +1 accumulation +1 correct -0.5 usage ( ) -0.5 i/o errors 3/4

+1 idea +1 init +0 accumulation +1 correct 3/4 count

+1 idea +1 init +1 accumulation +0 correct 3/4 n